Showing papers by "William Small published in 1994"

Contrast-enhanced spiral CT of the liver: effect of different amounts and injection rates of contrast material on early contrast enhancement.

Abstract: Spiral CT allows rapid hepatic imaging during a single breath-hold. The increase in imaging speed potentially allows contrast material to be used more efficaciously than with conventional dynamic CT, perhaps allowing a decrease in the volume of required contrast agent. To determine how this can be accomplished, we studied the effect of different bolus IV injection rates and amounts of contrast material on early hepatic enhancement during dynamic bolus spiral CT.A group of 20 healthy male volunteers were divided into four groups of five each. The groups received 75, 100, 125, or 150 ml of contrast material (Omnipaque 300, 300 mg l/ml). Each person within each group was scanned as contrast material was injected at rates of 3, 4, and 5 ml/sec. Hepatic enhancement was evaluated by comparing quantitative regions of interest before and after bolus injection of contrast material. Variations in enhancement produced by changes in volume and injection rate of contrast material were evaluated on early, middle, and l...

Enhancement effects of a hepatocyte receptor-specific MR contrast agent in an animal model.

Abstract: The enhancement characteristics of the liver and spleen produced by a hepatocyte-specific magnetic resonance imaging agent, an arabinogalactan-coated ultrasmall superparamagnetic iron oxide derivative, BMS 180550, were evaluated. Both heavily T1- and T2-weighted sequences were used. Imaging was performed in the farm pig model, as a function of contrast agent concentration (5, 10, and 20 mumol of iron per kilogram) and delay (immediate, 0.5, 2.5, 5.0, 7.5, and 9.0 hours) after bolus injection of BMS 180550. BMS 180550 provided excellent contrast enhancement characteristics by producing marked positive enhancement with T1-weighted sequences and marked negative enhancement with T2-weighted sequences. The T1-weighted enhancement immediately after contrast agent injection was of greater magnitude in the spleen (329% +/- 83) than in the liver (66% +/- 16). Postcontrast negative enhancement with T2-weighted sequences was largely hepatocyte specific at 5 and 10 mumol/kg but was also seen within the spleen at 20 mumol/kg. The authors discuss the possible mechanisms that produce these changes and conclude that 10 mumol/kg BMS 180550 is near the optimum dose for maximizing the enhancement properties of this agent with all sequences in the farm pig.

Does CTAP prior to hepatic resection improve patient survival rates

Abstract: The purpose of our study was to compare survival rates of colon carcinoma patients who had undergone attempted curative hepatic resection based on liver staging by computed tomographic angiography (CTA) or portography (CTAP) with previously reported survival rates of patients who underwent similar surgery without preoperative CTAP evaluations A total of 404 CTAP studies performed at three institutions were reviewed Of this group, 197 had colon carcinoma Sixty-nine of the colon patients went to surgery Actuarial adjusted yearly survival rates were calculated for the prior CTAP colon group and compared to historical controls The control survival data were taken from reports published prior to the CTAP era Our study demonstrated no difference in the 1-year survival data between the groups However, the CTAP patients had greater survival in years 2–4 This greater survival may be multifactorial but in part due to better surgical selection caused by CTAP

CT angiography and CT arterial portography in evaluation of hepatic adenomas.

Abstract: OBJECTIVE Our goal was to evaluate the contribution of CT arterial portography (CTAP) and CT angiography to accurate determination of disease extent in patients with known hepatic adenomas. MATERIALS AND METHODS Imaging results were reviewed in three women with known hepatic adenomas, all of whom had percutaneous biopsy to confirm the diagnosis. Results of CTAP studies in all patients as well as results of CT arteriography in one patient were compared with routine dynamic CT studies in all three and with MRI studies in two. RESULTS The CTAP and CT arteriography demonstrated multiple additional lesions in all patients as compared with routine dynamic CT and MRI studies. In one of the patients who was found to have hepatic adenomatosis, the degree of tumor involvement changed the operative procedure from partial hepatectomy to liver transplantation. CONCLUSION In patients with known hepatic adenomas who require surgery, CTAP provides more accurate preoperative staging of extent of liver replacement with tumor.